The new alignment method works

Closes #1

README.md

@@ -5,4 +5,4 @@
 Typeset provides utilities for text layout, wrapping, and rendering.
 
 The state of a text layout is stored in a TypeSetter, and it can be drawn to any
-image.Image using a Drawer which "extends" TypeSetter.
+draw.Image using a Drawer which "extends" TypeSetter.

layout.go

@@ -116,12 +116,10 @@ type LineLayout struct {
 func DoLine (text []rune, face font.Face, wrap bool, width fixed.Int26_6) (line LineLayout, remaining []rune) {
 	remaining    = text
 	x           := fixed.Int26_6(0)
-	lastWord    := WordLayout { }
 	isFirstWord := true
 	for {
 		// process one word
 		word, remainingFromWord := DoWord(remaining, face)
-		word.X = x
 		x += word.Width
 
 		// if we have gone over the preferred width, stop processing
@@ -135,7 +133,6 @@ func DoLine (text []rune, face font.Face, wrap bool, width fixed.Int26_6) (line
 
 		// if the word actually has contents, add it
 		if word.Runes != nil {
-			lastWord   = word
 			line.Words = append(line.Words, word)
 		}
 
@@ -151,9 +148,12 @@ func DoLine (text []rune, face font.Face, wrap bool, width fixed.Int26_6) (line
 	}
 
 	// set the width of the line's content.
-	line.ContentWidth = lastWord.X + lastWord.Width
 	line.Width = width
-	line.SpaceAfter = lastWord.SpaceAfter
+	if len(line.Words) > 0 {
+		lastWord := line.Words[len(line.Words) - 1]
+		line.ContentWidth = x - lastWord.SpaceAfter
+		line.SpaceAfter   = lastWord.SpaceAfter
+	}
 	return
 }
 
@@ -170,30 +170,45 @@ func (line *LineLayout) Length () int {
 
 // Align aligns the text in the line according to the specified alignment
 // method.
-func (line *LineLayout) Align (align Align) {
+func (line *LineLayout) Align (align Align, tabWidth fixed.Int26_6) {
 	if len(line.Words) == 0 { return }
 	
 	if align == AlignEven {
-		line.justify()
-		return
-	}
+		line.justify(tabWidth)
+	} else {
+		line.contract(tabWidth)
+		
+		var leftOffset fixed.Int26_6
+		if align == AlignMiddle {
+			leftOffset = (line.Width - line.ContentWidth) / 2
+		} else if align == AlignEnd {
+			leftOffset = line.Width - line.ContentWidth
+		}
 
-	leftOffset := -line.Words[0].X
-
-	if align == AlignMiddle {
-		leftOffset += (line.Width - line.ContentWidth) / 2
-	} else if align == AlignEnd {
-		leftOffset += line.Width - line.ContentWidth
-	}
-
-	for index := range line.Words {
-		line.Words[index].X += leftOffset
+		for index := range line.Words {
+			line.Words[index].X += leftOffset
+		}
 	}
 }
 
-func (line *LineLayout) justify () {
-	if len(line.Words) < 2 {
-		line.Align(AlignStart)
+// assume line has content > 0
+func (line *LineLayout) contract (tabWidth fixed.Int26_6) {
+	x := fixed.Int26_6(0)
+	for index, word := range line.Words {
+		word.X = x
+		x += word.Width
+		x += word.SpaceAfter
+		line.Words[index] = word
+	}
+	lastWord := line.Words[len(line.Words) - 1]
+	line.ContentWidth = lastWord.X + lastWord.Width
+	line.SpaceAfter   = lastWord.SpaceAfter
+}
+
+// assume line has content > 0
+func (line *LineLayout) justify (tabWidth fixed.Int26_6) {
+	if len(line.Words) <= 1 {
+		line.Align(AlignStart, tabWidth)
 		return
 	}
 

setter.go

@@ -18,6 +18,7 @@ type TypeSetter struct {
 	face           font.Face
 	width, height  int
 	wrap           bool
+	tabWidth       fixed.Int26_6
 	
 	minWidth          fixed.Int26_6
 	layoutBounds      image.Rectangle
@@ -117,7 +118,7 @@ func (setter *TypeSetter) alignHorizontally () {
 		}
 
 		// align line
-		setter.lines[index].Align(align)
+		setter.lines[index].Align(align, setter.tabWidth)
 	}
 }
 
@@ -215,6 +216,14 @@ func (setter *TypeSetter) SetHeight (heignt int) {
 	setter.height = heignt
 }
 
+// SetTabWidth sets the distance between tab stops.
+func (setter *TypeSetter) SetTabWidth (tabWidth fixed.Int26_6) {
+	if setter.tabWidth == tabWidth { return }
+	setter.layoutClean = false
+	setter.alignClean  = false
+	setter.tabWidth = tabWidth
+}
+
 // Em returns the width of one emspace according to the typesetter's font, which
 // is the width of the capital letter 'M'.
 func (setter *TypeSetter) Em () (width fixed.Int26_6) {
@@ -386,10 +395,10 @@ func (setter *TypeSetter) MinimumSize () image.Point {
 	return image.Pt(width.Round(), height.Round())
 }
 
-// ReccomendedHeightFor returns the reccomended max height if the text were to
-// have its maximum width set to the given width. This does not alter the
+// RecommendedHeight returns the reccomended max height if the text were to have
+// its maximum width set to the given width. This does not alter the
 // typesetter's state.
-func (setter *TypeSetter) ReccomendedHeightFor (width int) (height int) {
+func (setter *TypeSetter) RecommendedHeight (width int) (height int) {
 	setter.needLayout()
 	
 	if setter.lines == nil { return }